General Physiology First Aid Extra Info Flashcards Preview

CPR Week 6 > General Physiology First Aid Extra Info > Flashcards

Flashcards in General Physiology First Aid Extra Info Deck (32)
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1
Q

Formula for determining Physiologic dead space

A

Taco Paco Peco Paco

Vt = Tidal Volume
PaCO2 = arterial PCO2
PECO2 = expired air PCO2
Vd = Physiologic dead space

Vd = Vt x (PaCO2 - PECO2)/(PaCO2)

2
Q

Minute Ventilation (VE)

A

Total volume of gas entering the lungs per minute

VE = Vt x RR

RR = Respiratory Rate

3
Q

Alveolar Ventilation (VA)

A

Volume of gas per unit time that reaches the alveoli

VA = (Vt - Vd) x RR

4
Q

There is a tendency for the lungs to ________ and for the chest wall to _____.

A

Lungs to collapse inward and the chest wall to spring outward

5
Q

At the FRC, what are the pressures of the lungs?

A

Inward pull of the lung is balanced by outward pull of chest wall and system pressure is atmospheric

6
Q

At FRC, airway and alveolar pressures are ____ and intrapleural pressure is ____ which prevents _____.

____ is at a minimum.

A

Zero, negative, pneumothorax, PVR

7
Q

2 forms of the hemoglobin chains

A
T = Taut form - Has low affinity for O2
R = Relaxed form - Has high affinity for O2 (300x)
8
Q

What favors the taut form of hemoglobin?

A

Increased Cl, H+, CO2, 2,3-BPG, and temperature since these shift the dissociation curve to the right, leading to increased O2 unloading

9
Q

Why does fetal hemoglobin have higher affinity for O2 and what are the chain type differences

A

Fetal Hb is made of 2a and 2y chains. This causes fetal hemoglobin to have a lower affinity for 2,3-BPG than adult Hb, and thus has higher affinity for O2.

10
Q

When is hemoglobin taut vs. relaxed?

A

Taut in Tissues

Relaxed in Respiratory tract

11
Q

What is methemoglobin?

A

Oxidized form of Hb (ferric, Fe3+) that does not bind O2 as readily, but has increased affinity for cyanide (iron in Hb usually is in a reduced state of Fe2+)

12
Q

How does methemoglobinemia present?

A

Cyanosis and chocolate colored blood

13
Q

How do you treat cyanide poisoning?

A

Use nitrites to oxidize Hb to methemoglobin, which binds cyanide. Use thiosulfate to bind this cyanide, forming thiocyanate, which is renally excreted

14
Q

Treatment of methemoglobinemia can be treated with what?

A

Methylene blue

15
Q

Nitrites cause poisoning by____________.

A

oxidizing Fe2+ to Fe3+

16
Q

What is carboxyhemoglobin and what does it do to normal hemoglobin?

A

CO bound to Hemoglobin which shifts the dissociation curve to the left due to a decreased O2 binding capacity, causing a decreased O2 unloading in tissues.

17
Q

What is PVR?

A

Pulmonary Vascular Resistance

PVR = (Pressure in pulmonary artery - Pulmonary wedge pressure or pressure in the left atrium) / Cardiac output

18
Q

What is the alveolar gas equation?

A

PAO2 = PIO2 - (PaCO2/R)

PIO2 = PO2 of inspired air
PaCO2 = arterial PCO2
R = respiratory quotient = CO2 produced/O2 consumed

We can also just do:
150 - PaCO2/0.8

19
Q

Calculate A-a gradient

A

PAO2 - PaO2 = 10-15mmHg

20
Q

When might we see an increased A-a gradient?

A

May occur in hypoxemia, causes include shunting, V/Q mismatch, fibrosis (impairs diffusion)

21
Q

When we have Hypoxemia but a normal A-a gradient, what could be the cause?

A

High altitude or hypoventilation

22
Q

When we have hypoxemia but an increased A-a gradient, what could be the cause?

A

V/Q mismatch, diffusion limitations, right to left shunt

23
Q

Causes of hypoxia

A

Decreased Cardiac output
hypoxemia
anemia
CO poisoning

24
Q

Causes of ischemia or loss of blood flow

A

Impeded arterial flow or a decreased venous drainage

25
Q

Ideal situation for V/Q?

A

V/Q = 1 which would indicate ventilationm atching perfusion for adequate gas exchange

26
Q

V/Q for the apex and what is indicates

A

= 3, which means wasted ventilation

27
Q

V/Q for the base of the lung and what it indicates

A

= 0.6 and indicates wasted perfusion

28
Q

What is true about ventilation and perfusion at the base of the lung?

A

They are both greatest there than at the apex

29
Q

With exercise there is _____ in apical capillaries resulting in a V/Q ratio that approaches ______.

A

Vasodilation, approaches 1

30
Q

Why does TB affect the upper lobes?

A

Thrive in high O2 conditions

31
Q

Discuss what a V/Q = 0 indicates and the effect of 100% O2 added to the system

A

Indicates a shunt = airway obstruction. In a shunt, 100% O2 does not improve PO2

32
Q

Discuss what a V/Q = infinite indicates and the effect of 100% O2 added to the system

A

Blood flow obstruction = dead space. Assuming <100% dead space, 100% O2 improves PO2